The present invention relates to a wheat powdery mildew control medicament which is prepared by weighing rhubarb, Chinese prickly ash, radix euphorbiae lantu, Sculellaria barbata, cortex phellodendri, dandelion, euphorbia humifusa and Chinese yam, crushing, blending, soaking in ethanol, shaking for extraction, after centrifugation, rotatably evaporating a supernatant to obtain paste, diluting the paste with water, and adding potassium dihydrogen phosphate and 15% triadimefon to prepare a finished product. Active ingredients of the components are extracted and mxied with the potassium dihydrogen phosphate and the triadimefon, the amount of the triadimefon is reduced, the wheat powdery mildew control medicament is sprayed directly to wheat fields, the treatment effect is good, the cure rate is over 97%, and the wheat powdery mildew control medicament has good growth-promoting effect on cured plants, and can reduce the impact of large-scale production reduction.